1. Field of the Invention
The present invention relates to an overheat protection device for a scroll compressor, and in particular to an improved overheat protection device for a scroll compressor which can prevent a sealing member from being damaged due to the overheat, by detecting a gas temperature in the compressor and directly stopping driving of the compressor, without using a special controller, when the gas temperature exceeds an adequate temperature.
2. Description of the Background Art
In general, compressors are divided into reciprocating compressors, scroll compressors, centrifugal compressors (generally, xe2x80x98turbo-compressorsxe2x80x99) and sliding vane compressors (generally, xe2x80x98rotary compressorsxe2x80x99).
Here, the scroll compressor inhales, compresses and discharges a gas by using a rotary body, similarly to the centrifugal compressor or the sliding vane compressor.
The scroll compressors are divided into low pressure scroll compressors and high pressure scroll compressors according to whether a suction gas or a discharge gas is filled in a casing.
FIG. 1 is a half cross-sectional diagram illustrating a vertical scroll compressor of the conventional low pressure scroll compressors.
As depicted in FIG. 1, in the conventional vertical scroll compressor, an upper frame 2 and a lower frame (not shown) are respectively fixed to the upper and lower sides of a vertical casing 1 in which oil is filled at a predetermined height; and a driving motor 4 consisting of a stator 4A and a rotor 4B is firmly fixed between the upper frame 2 and the lower frame (not shown).
A driving shaft 5 is rotatably inserted into the center of the rotor 4B of the driving motor 4, passing through the upper frame 2.
In addition, a wrap 6a is formed in an involute curve at an upper surface of a main frame 2, and an orbiting scroll 6 eccentrically connected to the driving shaft 5 is rotatably positioned. A fixed scroll 7 having a wrap 7a formed in the involute curve in order to compose a plurality of compression chambers by being engaged with the wrap 6a of the orbiting scroll 6 is fixedly disposed at the upper frame 2.
Above the fixed scroll 7, a discharge cover 8 dividing the inside of the casing 1 into a high pressure region and a low pressure region is fixed to the inner circumferential surface of the casing 1. A valve assembly 9 consisting of a valve housing 9A and a valve 9B are provided on a gas discharge hole 8a of the discharge cover 8 in order to prevent a reverse-flow of the gas.
Also, an overload protector (OLP) 10 for detecting an inside temperature of the casing 1, namely a temperature of the gas inhaled into the casing 1, and for stopping the compressor by intercepting power applied to the driving motor 4 in the case that the gas temperature exceeds an adequate temperature is provided above the stator 4A of the driving motor 4, in a connection state as shown in FIG. 2.
Reference numerals 5a and 7b denote an oil path and a discharge port, respectively. Reference marks SP and DP denote a suction pipe and a discharge pipe, respectively.
The operation of the conventional scroll compressor will now be explained.
When the power is applied, the rotor 4B rotates with the driving shaft 5 by the power at an inner portion of the stator 4, thereby eccentrically rotating the orbiting scroll 6 correspondingly to an eccentric distance. At the same time, the orbiting scroll 6 performs an orbiting movement correspondingly to an orbiting radius, centering around the shaft, thereby forming the plurality of compression chambers between the fixed scroll 7 and the wraps 6a, 7a. 
The plurality of compression chambers move to the center according to the constant orbiting movement of the orbiting scroll 6, a volume thereof being reduced. Accordingly, an inhaled refrigerant gas is more compressed, and externally outputted through the discharge port 7b of the fixed scroll 7.
At this time, the low pressure refrigerant gas is inhaled into the low pressure region of the casing 1 through the suction pipe SP, and inhaled into the compression chamber by the orbiting movement of the orbiting scroll 6. The overload protector 10 is provided at the low pressure region of the casing 1. Therefore, the overload protector 10 detects a temperature of the refrigerant gas filled in the low pressure region, and stops the compressor by intercepting the power applied to the driving motor 4, when the temperature exceeds the optical temperature.
However, in the conventional scroll compressor, the discharge gas discharged through the discharge port 7B is mixed with oil. When the temperature of the discharge gas abnormally rises, the oil is combusted (carbonized), or the gas in the compression chamber is overheated, thereby dissolving a tip seal inserted into the end portions of the wraps 6a, 7a. As a result, reliability of the compressor is reduced, and a life span of an air conditioner including the compressor is decreased.
In order to overcome such disadvantages, there was suggested a scroll compressor including a discharge gas temperature detection device as shown in FIG. 3.
According to the aforementioned scroll compressor, a thermostat 20 for detecting the temperature of the discharge gas is connected to the controller connected to the overload protector 10 at the high pressure region of the casing 1, and stops the compressor when the temperature of the discharge gas exceeds the adequate temperature.
However, the conventional scroll compressor having the thermostat needs a special controller, and thus cannot be used for a mechanical system, such as a window type air conditioner which does not have the controller.
Accordingly, it is an object of the present invention to provide an overheat protection device for a scroll compressor which can detect a gas temperature in a casing without employing a special controller, and directly stop driving of the compressor when the temperature exceeds an adequate temperature.
In order to achieve the above-described object of the present invention, in a scroll compressor having in a casing an orbiting scroll and a fixed scroll for inhaling, compressing and discharging a gas, and a driving motor for driving the orbiting scroll, there is provided an overheat protection device for the scroll compressor stopping the driving motor when a detected temperature exceeds an adequate temperature, a temperature detection device for detecting a temperature of the gas of a low pressure region where the gas is inhaled and a high pressure region where the gas is discharged through a discharge port of the fixed scroll being connected between a power terminal and the driving motor in an electrical serial state.